FIG. 1 illustrates the tape format of a conventional digital audio tape (DAT) recorder in which information is recorded along helical tracks. As illustrated, music program regions are provided along the length of a magnetic tape 1. In each music program region, digital audio data for one piece of music and additional information, such as a start ID (identification) for high speed indexing, the piece-of-music number, the time code, and the like are recorded.
FIG. 2 illustrates the composition of one of the helical tracks 3 forming the music program region. As illustrated, each track comprises marginal areas 4 on both ends, subcode areas 5, auto-tracking areas 6, a PCM area 7, and interblock gaps 8. Digital data representing the audio signal is recorded in the PCM area 7.
Additional information (the start ID, the piece-of-music number, the time code, etc.) is recorded in the subcode areas 5 or the PCM area 7. The start ID is written in the subcode areas 5 of 600 tracks at the beginning of each program region. An identical start ID is written over 600 tracks so as to permit high speed indexing (e.g., at a speed 200 times higher than the normal playback speed).
The auto-tracking areas 6 are for recording information used for tracking. For the purpose of tracking, the head scanning is controlled such that the amounts of crosstalk component from the pilot signals on both adjacent tracks are equal. The interblock gaps 8 are provided to permit independent writing and overwriting in the subcode areas 5. This allows post production recording of the subcode areas 5.
The conventional DAT is composed in the above manner. When a video signal is to be recorded on the magnetic tape with the above format, the video signal of one frame, i.e., picture data segment, is recorded in the same way as the audio digital data of one piece-of-music is recorded over one music program region. When an NTSC standard video signal (resolution: 910 dots horizontal.times.525 lines vertical) is to be recorded, 166 tracks are required for one picture data segment. Thus, the number of tracks required for the recording of the picture data segment is smaller than the number of tracks (which is 600) over which the start ID is to be recorded for the high speed indexing. As a result, no picture data is recorded in the 434 (600-166) tracks, and the tracks of the tape are not fully utilized.
Another problem of the conventional DAT is the inability to record the video signals of different systems, such as NTSC and PAL, onto a single magnetic tape.
An additional problem is inability to align timing in recording and playback taking each picture as a unit.
A further problem is that, due to head writing timing deviations, the basic track quantity cannot be maintained during overwrite.